Closes #969

[actvabdulrahman]

Summary

• Investigated issue Implement governance proposal submission and voting API #969 ("Implement governance proposal submission and voting API") and found the 4 requested REST endpoints already exist off-chain (proposal creation, list, detail, vote — see src/modules/keys/keys.routes.ts and src/modules/creators/creators.routes.ts), including eligibility checks and DB-level double-vote prevention (@@unique([keyId, proposalId, voter])). No governance smart contract exists yet in accesslayer-contracts, so real on-chain submission and event-driven state sync are genuinely blocked, not something this PR can complete — see "Scope descoped" below.
• Found and fixed one real, concrete bug uncovered during that investigation: castKeyProposalVote inserted a GovernanceVote row but never updated GovernanceProposal.totalVotingWeight or results, so list/detail tallies were immediately stale after every vote cast.
• Fix: inside the existing atomic $transaction, the proposal is re-read, its active status re-checked, and a new pure helper applyVoteWeight increments totalVotingWeight and results[optionIndex] alongside the vote insert and activity log — all in the same transaction, so a vote can never be recorded without its tally updating (or vice versa).
• Added src/modules/keys/key-proposal-votes.service.test.ts with mocked-Prisma unit tests covering applyVoteWeight directly (single vote, repeated same option, distinct options tracked independently, untouched result buckets preserved, large totals without floating-point drift via toBigInt) and the full castKeyProposalVote flow (tally accumulation across 3 distinct wallets/options, and every existing guard still enforced: DuplicateVoteError, HolderNotEligibleError, OptionIndexOutOfRangeError, closed-proposal rejection).

Scope descoped (blocked, tracked for a follow-up issue): real on-chain contract submission (create_proposal/cast_vote are currently TODO stubs; submitTransaction is a non-functional placeholder; no governance contract or Soroban client binding exists in this repo) and event-driven proposal-state sync (no Soroban event fetcher exists anywhere in the codebase; the existing governance-sync.job.ts only does time-based expiry). Both require a governance contract to be defined in accesslayer-contracts first — attempting them here would mean building against something that doesn't exist.

Testing

• pnpm lint
• pnpm build
• pnpm exec prisma generate when schema or generated types changed

(No Prisma schema changes were made — this fix only touches service logic and adds tests, so prisma generate isn't applicable. pnpm test src/modules/keys/key-proposal-votes.service.test.ts also run: 13/13 pass.)

Checklist

• Linked issue or backlog item
• No secrets or live credentials added
• Docs updated if setup or env changed
• Change is scoped to one problem

(No docs updates needed — no setup or environment variables changed; this is a pure bugfix within existing service logic.)

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#969	Implement governance proposal submission and voting API	Link to this issue

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